OK, what's in Mentos that makes Cola go bananas?

Question

Mentos can get a little expensive after awhile. I know it's just the coating, but what reacts with cola that way. Looking for an economical way to do this.

Answer 1

From http://membership.acs.org/C/Chicago/Statefair/CD-2005/ChmShort/CS04.html

August 2004

Mentos Mayhem
Kids, why do Mentos mints dropped into a can of soda make a foamy fountain? One might guess that the acid in the soda might be reacting with some kind of carbonate in the mint coating to create CO2 carbon dioxide fizz. Mentos have a strange chalky color and texture and they do taste a bit like antacid (calcium carbonate) tablets. However, the ingredients do not include carbonates or, for that matter, any other significantly alkaline material. Mint Mentos contain sugar (sucrose), glucose, coconut oil, starch, emulsifiers, natural flavor, and gum arabic. They are pretty much just big pellets of flavored sugar with gummy stuff added to give them structural integrity.

Drop a Mentos directly into a freshly opened full can of soda. But wait! First, make sure that the can is in a sink or tray to collect the significant amount of foam that will spill over. In our labs, a mint Mento and a diet cola provided the most foam, causing about half of the soda to be lost. Using the can makes the foaming more spectacular than if you poured the soda into a glass because of the small opening.

So why do Mentos make soda foam up? It's a physical reaction, not a chemical one. Ordinarily, water resists the expansion of bubbles in the soda. Water molecules attract each other strongly, forming a tight mesh around each bubble. It takes energy to push water molecules away from each other to form a new bubble, or to expand a bubble that has already been formed. The property is called surface tension. The oils, emulsifiers, and gum arabic from the dissolving candy disrupt the water mesh, so it takes less work to expand bubbles. At the same time, the roughness of the candy surface provides many little nooks and crannies (more surface area) that allow new bubbles to form more quickly. As more of the surface dissolves, both processes accelerate, and foam rapidly begins to form.

You can see a similar effect when cooking potatoes or pasta in a pot of boiling water. The water will sometimes boil over because organic materials that leach out of the cooking potatoes or pasta disrupt the tight mesh of water molecules at the surface of the water, making it easier for bubbles and foam to form. Root beer can also foam over if a scoop of ice cream is added, for essentially the same reason. The surface tension of the root beer is lowered by gums and proteins from the melting ice cream, and the CO2 outgassing from the root beer blows the foam.

Test this hypothesis by dropping a Mentos into orange juice or any acidic but non-carbonated drink, or by dropping a Mentos into completely flat soda. What happens? Why? (Mentos is a registered trademark of Van Melle USA Inc.)

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Notes:
Experiment suggested by Steven S. Trail (BP Chemicals).
As an interesting sidelight, teacher Lee Marek of Naperville North High School, Naperville, IL, developed this into a demo for the Letterman show.

References:
Fred Senese [e-mail],
http://antoine.frostburg.edu/chem/senese/101/consumer/faq/mentos.shtml

Answer 2

It's not what is in mentos it is how mentos is shaped.

These chemists are saying that the primary cause is physical, not chemical. Their explanation: nucleation sites. If you have a liquid that is supersaturated with gas (like soda, which is pumped full of carbon dioxide), a nucleation site is a place where the gas is able to form bubbles. Nucleation sites can be scratches on a surface or specks of dust – anywhere that you have a high surface area in a very small volume. That's where bubbles can form.

Mentos seem to be loaded with nucleation sites. In other words, there are so many microscopic nooks and crannies on the surface of a Mento that an incredible number of bubbles will form when you drop it in a bottle of soda. Since the Mentos are also heavy enough to sink, they react with the soda all the way to the bottom. The escaping bubbles quickly turn into a raging foam, and the pressure builds dramatically. Before you know it, you've got a big geyser happening!

Answer 3

I heard a report on NPR about this from a chemist. It's not the chemical structure of the Mentos, but the specific surface texture that causes the carbon dioxide suspended in the carbonated drink to very very very quickly come out of suspension. This rapid change of state causes the violent reaction of the liquid in the bottle.

Answer 4

It's one of the chemicals in Diet Coke that causes the little explosion. I saw it on David Letterman last night. 1 bottle and 1 pack of mentos should ease your curiosity.

Answer 5

What Is In Mentos

Answer 6

article I read said it is the ruff surface of the mentos, diet coke 2liter works best w/t 13 mentos no chemical reaction at all just physics try ruff rocks???

Answer 7

try attaching anything that will vibrate to the bottle, but instead of just taking the lid off, poke a small hole in the lid and put it back on. If you and a friend are drinking beer from a bottle, bang the bottom of your beer on the top of his. This has the same effect.

Answer 8

The Gum Arabic reacts with the sugar.

Answer 9

go to www.eepybird.com, they show a cool video of it and it explains why the mentos make the bottles explode.

Answer 10

YEA, THAT IS SOOO COOOL.

PUT MENTOS IN A BOTTLE OF COCA COLA OR PEPSI, OR EVEN 7-UP. YOU GET A COOL GEYSER.